The long term objective of this program project continues to be "to elucidate the role of biobehavioral factors in the etiology, pathogenesis and course of coronary heart disease (CHD)." Our three broad, programmatic objectives are to: 1) Evaluate the association between interrelated sets of psychosocial risk factors and behavioral and biological (including the cellular/molecular level) mediators of pathogenesis; 2) Identify environmental antecedents of the psychosocial/biobehavioral profile that increases pathogenesis; and 3) Evaluate in both humans and an animal model the possible role of reduced brain serotonergic function as a mediator of the clustering in certain individuals and low SES groups of psychosocial and biobehavioral mediators of pathogenesis. Methods: We are recruiting a community sample of 400 subjects, stratified on SES, race, and gender who will be studied during a 2.5 day admission to our GCRC. During that time they will undergo a lumbar puncture to provide cerebrospinal fluid (CSF) for assay of CSF 5-hydroxyindole acetic acid (5HIAA) a reliable measure of CNS serotonin turnover. They will also be subjected to serotonin- depletion using the tryptophan-depletion method and serotonin enhancement using iv tryptophan. We shall evaluate and compare the relationship of SES and CSF 5HIAA to the profile of psychosocial and biobehavioral risk factors, and the effects of serotonin depletion and enhancement on measures of mood, cardiovascular and neurodocrine function, as well as on responses of these functions to mental challenge. Results: We have now run 35 subjects (Ss) through the GCRC protocol, and, at the present rate of subject accrual, we anticipate that by the end of the current grant period on 30 July we will have over 60 completed subjects, putting us right on track to meet our recruitment targets. Preliminary examination of the data being collected on the GCRC protocol shows that all variables are within the expected range and showing expected changes - e.g., increased cardiovascular and neuroendocrine arousal with anger recall challenge. The tryptophan depletion protocol is functioning as expected, with plasma tryptophan levels falling to very low levels on the tryptophan depletion day. With 17% of the total sample now run, we have not begun data analyses regarding the major hypotheses. Inspection of the data currently available in conjunction with the aforementioned checks for appropriate range and responsivity has revealed a rather intriguing serendipitous finding. Among the first 11 subjects run through the tryptophan depletion arm, those with high CSF 5HIAA (indicating high brain serotonin turnover) have higher resting plasma norepinephrine (NE) than subjects with lower CSF 5HIAA prior to consuming the amino acid drink with tryptophan included on the first, placebo day. At 30 min. after consuming the drink, all Ss show a spike in NE that is larger in high 5HIAA Ss, despite their higher baseline level. On the second test day, at 30 min following consumption of the drink not containing tryptophan, the high 5HIAA Ss show a larger NE spike than on the placebo day, while the low 5HIAA Ss show a smaller peak. While the ultimate meaning of this observation remains to be determined, it is quite interesting that tryptophan depletion has opposite effects on plasma NE response to the unpleasant drink in high vs low 5HIAA Ss - suggesting that the CSF 5HIAA measure will produce important findings when we move toward our planned, more systematic analyses of the data. Even though not proposed in our original application, we have been collecting pilot data on a recently discovered serotonin transporter promoter polymorphism. The promoter region for the serotonin transporter has two alleles in humans, one long (l) and one short (s). Persons with the l/l genotype have been shown to make more transporter and to score lower on measures of neurotocism than persons with l/s or s/s. A recent study by Higley et al. found that the l/l genotype was associated with higher CSF 5HIAA levels in rhesus monkeys who were separated from their mothers from birth to six months of age. In mother-reared monkeys, however, transporter promoter genotype was unrelated to CSF 5HIAA. We will be able to evaluate this same relationship in the subjects being studied under our GCRC protocol - i.e., to test whether the l/l genotype is more strongly associated with higher CSF 5HIAA in lower than higher SES Ss. Significance: Results should enhance our understanding of the environmental and neurobiological bases of the clustering of psychosocial/biobehavioral risk factors and lead to improved approaches to prevention and treatment of cardiovascular disease.